Dissolved Potentially Toxic Elements in the Megacity River Network of Shanghai, China

Riverine water exposed to potentially toxic element (PTE) contamination is a vital concern worldwide due to its severe impact on ecosystems, economies, and human health. In this research, the pollution level, sources, behavior, and potential health risks of Li, Fe, As, Sr, Sb, and Pb in the Shanghai river network (SRN) during the high-flow season were comprehensively investigated and evaluated. The results showed that the six PTE concentrations (mu g/L) ranked (207.05) > Fe (11.30) > Sb (6.95) > Li (6.16) > As (3.45) > Pb (0.02). The heavy-metal pollution index (HPI) and Nemerow index (NI) revealed the moderate-toheavy to heavy pollution of studied PTEs with the mean values of 74.00 and 0.98, respectively. As and Sb were found to be the major contributors to the total toxic risk according to the hazard quotient/index (HQ/HI). The HI value of Sb for children exceeded 1, which indicated an obvious noncarcinogenic health risk via ingestion and dermal absorption exposure pathways, with children at higher risk. The possible origins of pollution were recognized as the geogenic process (Li, Fe, and Sr), industrial waste (Sb), and the combined action of agricultural and industrial activities (As and Pb) by the methods of correlation analysis (CA) and principal component analysis (PCA). Overall, the geochemistry behavior of PTEs in the dissolved phase displayed the potential for tracing regional environmental management levels, especially in a megacity.